when i used to carry those carts there was a very common failure of 1134A IC which caused stuff like this... this also causes the '1A bug' on those carts.
additionally, because of a poor placement of one of the resistors, when the case is opened up in the typical manner (at least on the models i've seen) it will snap off.
so, if you are getting wacky data in your attempted save file, or noticed the 1A happening (actually, your total time will be 26:26:26 if i remember correctly), then its more than likely a faulty 1134A IC, and it'll need to be replaced.
if its just straight up lack of memory, then check to see if the resistor is snapped off. if you slid the case to open it, more than likely its gone.
the resistor is 10k, 0603 package.
hope that helps!